Formation of deoxycorticosterone from progesterone in extraadrenal tissues: demonstration of steroid 21-hydroxylase activity in human aorta.

In the present investigation, we demonstrated the presence of steroid 21-hydroxylase activity in microsome-enriched fractions prepared from homogenates of aortal tissues of human abortuses and a prepubertal boy. The specific activities of this enzyme in microsomes prepared from aortal tissue of various abortuses varied but was similar to that found previously in microsomes prepared from human fetal kidney tissue. However, the specific activity of steroid 21-hydroxylase in microsomes prepared from smooth muscle tissue of the aorta of a prepubertal boy was extraordinarily high, viz., 705 pmol x h-1 x mg-1 protein. Thus the potential exists for the formation of deoxycorticosterone (DOC) in aorta, another tissue site of DOC action.